LTE is a standard for wireless data communications technology and an evolution of the Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS) standards. LTE increases the capacity and speed of wireless data networks using new digital signal processing (DSP) techniques and modulations. The LTE network architecture is an Internet Protocol (IP)-based system with significantly reduced transfer latency than the third generation architecture. Compared to earlier wireless networks such as 2G and 3G networks, the LTE wireless network operates on a separate wireless spectrum and is thus incompatible with earlier networks. The LTE standard can be used with many different frequency bands. In North America, 700/800 and 1700/1900 MHz are used; 800, 900, 1800, 2600 MHz are used in Europe; 1800 and 2600 MHz are used in Asia; and 1800 MHz is used in Australia.
LTE may provide a downlink peak rates of 300 Mbit/s, uplink peak rates of 75 Mbit/s and QoS provisions permitting a transfer latency of less than 5 ms in the radio access network. LTE has the ability to manage fast-moving mobiles and supports multi-cast and broadcast streams. LTE supports scalable carrier bandwidths, from 1.4 MHz to 20 MHz and supports both frequency division duplexing (FDD) and time-division duplexing (TDD).
Release 8 of the 3GPP specifications defines the LTE towards 4th generation systems, includes new requirements for spatial multiplexing—also referred to as Multiple Input Multiple Output (MIMO)—wherein the base station and user equipment (UE) communicate using two or more spatial streams. The goal is to increase both the overall capacity of a cell and the data rate that a single user can expect from the system. As a result of the increasing data rates and flexibility, the design and test of LTE systems differs in many ways from previous generations of cellular technology. In particular, LTE network device design and test present new challenges for which test equipment and measurement methods must be adapted.
In a conventional LTE system, signal processing for the UEs is converged in a powerful signal processing center including a plurality of function blocks. However, as the number of cells increasing, the computing capacity of function block is increased geometrically. The bandwidth between two function blocks is increased geometrically and the buffer is increased geometrically. Thus, the signal processing center may reach to its bottleneck due to heat, power, memory, and bus limitations.